Releasable tool holders



Sept. 25, 1956 A. J. MARTIN RELEASABLE TOOL HOLDERS Filed June 25, 1954 INVENTOR. Ammo/w JMA/emv BY 2770 N57 1 w m r J J l 3 M RELEASABLE TooL HOLDERS Anthony J. Martin, Livonia, Mich., assignor to Charles J. Martin '& Sons, a corporation of Michigan Application June 25, 1954, Serial No. 439,328 3 Claims. (Cl. 2 799 This invention relates to improvements in tool holders for holding taps, dies, drills and other cutting tools in automatic screw machines, drill presses and the like.

Numerous tool holders have been developed for use in holding taps, dies, drills and other cutting tools in the spindles of production machines such as automatic screw machines, gang drill presses and the "like'to protect the tools and the work in the event the tap, drill 'or other cutting tool sticks or in the event the work to be tapped, drilled or-cut has not been suitably prepared for the operation. However, none of the prior art constructions has proven to be both economical and completely satisfactory.

Therefore, it is the object of this invention to provide an improved and economical to manufacture .positive acting clutch type retractable tool holder for production machines that is universally adaptable for use in automatic screw machines, drill presses and other production equipment which will positively and accurately hold taps, drills and other cutting tools, which will release such a tool from being turned by its spindle if and when apredetermined torque is exceeded, and which will retract in the event the tap drill or other cutting tool fails to function allowing the spindle .to advance and complete its cycle of operation without damage 'to the production machine, spindle, tool holder or the tool carried thereby.

Other objects of the invention will become apparent by reference to the following detailed description taken in connection with the accompanying drawing, in which:

Fig. 1 is a vertical sectional view of a clutch type retractable tool-holder embodying the invention.

Fig. 2 is an exploded view of the spring loaded retractable tool holding mechanism.

Fig. 3 is an exploded view of the clutch mechanism.

Fig. 4 is a horizontal sectional view taken on the line 44 of Fig. 2. 7

Figs. 5 and 6 are horizontal 'elevational views taken on the lines 5-5 and -6==6 of Fig. "3 looking in the direction indicated by the arrows-showing respectively the cooperating clutch faces of the fixed and sliding clutch members preferably employed. t

Referring now to. the drawing wherein like minerals refer to like and corresponding parts throughout the several views, the clutch type retractable tool holder disclosed therein illustrative of the invention comprises a body 10 which is provided with a standard taper 11 at its upper end and which is bored and counter-bored from its lower end to provide a spring chamber 12, a tool holder retracting chamber 13, a clutch chamber 14 and an internally threaded end portion 15 which accommodates a lock nut 16 employed to hold the clutch mechanism and the retractable tool holder mechanism in assembled relationship within the said body 10.

Sleeve type clutch elements 17 and 18 having complementary clutch teeth 170 and 180 formed in adjacent annular ends thereof are first telescoped within the clutch chamber 14 of the body 10. The upper clutch element 17 is seated on the annular shoulder 19 and is 2,764,416 Patented Sept. 25, 1956 ceive theexternally splined end 2100 of the tool holding element 21. A compression spring 22, a thrust sleeve 2 3, washers 24 and 25 and the lock nut 16 complete the clutch mechanism and provide means for applying pressure onto the lower clutch element 18 whereby to releaseably maintain the reciprocable and rotatable lower clutch element 18 in engagement with the upper fixed clutch element 17.

The upper fixed clutch element 17 serves as a drive element to drive the lower spring loaded clutch element 18 which in turn serves as a drive element through which the tool holding element -2-1'splined therein for longitudinal movement in respect thereto is driven until the torque applied to the tool holding element 21 exceeds the permissible torque allowed to be transmitted from the body 10 to the toollholding element through the clutch elements 17 and 18, whereupon the clutch slips or clicks and ceases to drive the tool holding element 21.

The amount of torque permitted to be transmitted from the body 10 to the tool holding element 21 through the clutch mechanism depends upon the shape of the clutch teeth and 180, the strength of the compression spring 22, and the number and thickness of the washers 24 and 25 employed to adjust the compressive force of the said compression spring 22. It is therefore obvious that the clutch-drive portion of tool holders em"- bodying the invention are not only susceptible to wide ranges of torque resistance in their construction but the torque transmitted to the tool holding element may be readily adjusted to suit particular requirements.

The external splines 2108 at the upper end of the tool holding element 21 are of sufficient length to permit the said tool holding element to reciprocate from its extended position shown in Fig. 1 into the'tool holder retracting chamber 13. The lower end of the tool hold= ing element 21 is provided with an internal or female taper 210 to receive cutting tools-such as a tap- 26 as indicated in Fig. 1. The upper end of, the tool holding element 21 is bored and threaded at 27 to accommodate a spring load adjusting screw 28 and is 'counterbored at 29 to telescopingly receive the lower end of a retracting resisting compression spring 30. The lower end of the tool holding element 21 is reduced in diameter at 31 to provide an annular shoulder 32 which bea'r's'on the upper washer 24. By reference to Fig. 1, it will be noted that the same lock nut 16 and washers 24 and 25 that mai-ntainthe clutch mechanism in assembled relationship'within'the body 10 also retains the tool holding ele-' ment 21 within the clutch mechanism.

ln assembling the tool holding mechanism within the clutch mechanism, the washers 24 and 25 and the lock nut 16* are removed, the retraction resistingcompression spring 30 is positioned in the spring chamber 12, the tool holding element 21 is telescoped onto the compression spring 30 and the external splines 2100 thereof are telescoped through the female splines 1800 of the clutch element 18. The washers 24 and 25 and the lock nut 16 are then telescoped onto the reduced end 31 of the tool holder 21, and the lock nut 16 is threaded into the internally threaded end 15 of the body 10.

The retraction resisting compression spring 38 is of such strength as will resiliently hold the tool holding element 21 in its fully extended position within the body 10 as indicated in Fig. 1 during normal operation of a tool held therein. The resistance preventing the retraction of the tool holding element may be varied both by using a spring 30 of a greater or lesser compressive resistance or the spring resistance may be increased or de- (not shown) and engage the end of the tool 26 to remove the said tool 26 from the internal taper 210 of the tool holding element 21. A suitable longitudinal groove 36 is provided along the outer periphery of the thrust sleeve 23 into which the inner end of a. set screw 37 threaded through the body extends for the purpose of maintaining the slots 34 of the thrust sleeve 23 in circumferential alignment with the slots 33 and 35 of the body and tool holding element respectively. A set screw 38 is employed to fix the lock nut 16 in the position to which it is threaded in the lower end of the body 10.

When a clutch type retractable tool holder embodying the invention is employed for drilling or tapping or other operations, and the tool carried by the tool holding element 21 is applied to the work, if the torque required to accomplish the operation becomes excessive, the clutch elements 17 and 18 slip to prevent further rotation of the tool whereby to eliminate possible damage to or breakage of the tool spindle, the tool holder, the tool or the work is avoided. If the advance of the tool into the work is prevented by conditions not normal to the operation, the tool will retract within the clutch, and like and similar damage or breakage is avoided.

This improved tool holder has been found to be extremely rugged, positive in its functioning, economical to manufacture and readily maintained. Furthermore, it is readily adjustable for use with various types of work to safeguard the machine tool, the spindle, the tool holder and the work from breakage or spoilage due to unexpected conditions encountered in drilling or tapping or in other operations where the tool is advanced to the work or vice versa.

Although but one specific embodiment of the inven tion has been disclosed and described herein, it is obvious that many changes may be made in the size, shape, arrangement and detail of the various elements of the invention, all without departing from the spirit and scope thereof or defined by the appended claims.

I claim:

1. A clutch type retractable tool holder comprising a bored and counterbored body portion, an annular clutch element fixed within said body portion, a second annular clutch element reciprocally and rotatably mounted within said body portion, spring means resiliently urging said second annular clutch element into engage ment with said fixed clutch element, adjacent annular faces of said clutch elements having interengaging beveled teeth therein, a tool holder reciprocatingly mounted within said clutch elements splined in axially slidable and rotatably driven relationship within said second annular clutch element, means retaining said second annular clutch element and said tool holder within said body portion, compression spring means reacting against said body portion resiliently holding said tool holder against said retaining means, and means for varying the pressure of said compression spring means whereby to vary the torsion at which said clutch will slip.

2. A clutch type retractable tool holder comprising a body portion, an annular clutch element fixed within said body portion, an annular rotatable and slidable internally splined clutch element within said body portion disposed in alignment with said fixed clutch element, said clutch elements having interengaging clutch faces formed in adjacent annular ends thereof, an annular thrust sleeve slidably mounted within said body portion in axial alignment with said clutch elements, spring means disposed between said slidable clutch element and said thrust sleeve resiliently maintaining said clutch elements in engagement, an externally splined tool holding element reciprocatingly mounted in said sleeve element having one end thereof telescopingly engaged by the internal splines of said slidable clutch element, means for retaining said movable clutch and tool holder elements in said body portion, and spring means disposed axially between said body portion and said tool holding element constantly urging said tool holder element toward said retaining means.

3. A clutch type retractable tool holder comprising a body portion, an annular clutch element fixed within said body portion, an annular rotatable and slidable internally splined clutch element within said body portion disposed in alignment with said fixed clutch element, said clutch elements having interengaging clutch faces formed in adjacent annular ends thereof, an annular thrust sleeve slidably mounted within said body portion in axial alignment with said clutch elements, spring means disposed between said slidable clutch element and said thrust sleeve resiliently maintaining said clutch elements in engagement, *an externally splined tool holding element reciprocatingly mounted in said sleeve element having one end thereof telescopingly engaged by the internal splines of said slidable clutch element, a single means for retaining said movable clutch and tool holder elements in said body portion, spring means disposed axially between said body portion and said tool holding element constantly urging said tool holder element toward said retaining means, the said body portion, thrust sleeve and tool holding element having aligned transverse slots therethrough to receive a bar to permit ready removal of a tool carried thereby, and means for maintaining the said thrust sleeve slot in alignment with the others.

References Cited in the file of this patent UNITED STATES PATENTS 915,568 Douglas Mar. 16, 1909 927,028 Errington July 6, 1909 2,286,088 Harrell June 9, 1942 2,482,995 Willis Sept. 27, 1949 FOREIGN PATENTS 654,203 Great Britain June 13, 1951 

